void fit() {
   TF1 *f1= new TF1("f1","[0]*TMath::Exp(-1*(x-[1])*(x-[1])/4/[2]/[2]) + [3]x*x*x + [4]*x*x + [5]*x + [6]",0,3);
   f1->SetParameters(1,1,1,1,1,1,1);
   TFile f("hm.root");
   TH1F h2 = f.Get("h2");
   h2.Fit("f1","","",1,1.2);

}
